Various techniques are already known for producing coloured patterns or designs on nap or pile fabrics. Thus, for example, the Jacquard weaving process may be employed to interweave different yarns or undyed yarns have differing affinities for dyes subsequently applied, so that a two-tone effect is produced during the dyeing stage.
It is also possible for two-tone effects to be produced by printing nap fabrics with paste dye with or without the addition of chemical swelling agents. Also a previously dyed nap fabric, having a nap consisting of acrylic fibers, may be printed with contrast-forming agents such as ethylene carbonate or propylene carbonate, the fabric being subjected after drying to an electropolishing process.
These known methods for giving a nap fabric a two-tone effect are however very unsatisfactory from the practical point of view, being time consuming and requiring expensive equipment.